Directed by Sean Hartofilis, "Beach Pillows" centers on two childhood friends who postpone taking responsibility in life. Mr. Kartheiser plays one of the friends. "He's a lives-in-the-moment kind of guy who doesn't really see the need to plan ahead," says Mr. Kartheiser, 33, speaking by phone last month. The other friend is played by real-life pal Geoffrey Arend (ABC's "Body of Proof"), who's married to "Mad Men" star Christina Hendricks. The movie does not yet have a release date.

"Parents tend to take care of their kids so much longer than they used to -- They make sure that there's a net under them all the way into their 30s, sometimes their 40s," he explains. Case in point, he says: Many of the interns on the set of "Beach Pillows" still live with their parents.

"This is a story about two guys who have been taking advantage of that and haven't really had to step up and take risks in their lives."

As for the movie's curious title, he insists it's not a euphemism for something naughty. "It's an idea that one of our characters has for a wonderful piece of merchandise," he says, cryptically.

This is Mr. Kartheiser's first time on Long Island, a region he fondly associates with the movies of LI-based independent filmmaker Hal Hartley. "I had no idea the sand on Long Island was so fine and white," he says. He's been dividing his time between Long Island, Manhattan (where he's roommates with Arend) and Los Angeles, where he travels every weekend.

In August, he starts rehearsals for "The Death of the Novel" at the San Jose Repertory Theatre -- he'll play a novelist coping with grief after 9/11. "It's an interesting story about the mental state of someone who's had a lot of loss and trauma in his life, and how a person who tends to be very intellectual responds to that level of emotional pain," he says.

Mr. Kartheriser says he's not yet sure when production on the sixth season of "Mad Men" will begin. In the meantime, he's still shedding the 25 pounds he gained to play Pete in Season 5. "I put a lot of it back on this week," he jokes. "I went to a wedding in wine-tasting country, and I think I gained like 10 pounds."